When I went to check the mintages out of interest I realised that there were no 1oz Gold proofs released individually so from what I can gather these coins must have been separated out of the 3 coins sets that were issued (containing 1oz, 1/4oz and 1/10oz) meaning the number available is quite low. It seems there was some interest in the 3 coin sets initially with the Mouse and Ox sets achieving the highest number of sales, but with numbers soon dropping later:

Year

Denomination

Description

Mintage

Sales

1996

$100, $25, $15

(1oz, 1/4oz, 1/10oz) Three-coin set Year of the Mouse

3,888

2,886

1997

$100, $25, $15

(1oz, 1/4oz, 1/10oz) Three-coin set Year of the Ox

3,888

3,146

1998

$100, $25, $15

(1oz, 1/4oz, 1/10oz) Three-coin set Year of the Tiger

3,800

1,918

1999

$100, $25, $15

(1oz, 1/4oz, 1/10oz) Three-coin set Year of the Rabbit

3,800

1,634

2000

$100, $25, $15

(1oz, 1/4oz, 1/10oz) Three-coin set Year of the Dragon

3,000

2,886

2001

$100, $25, $15

(1oz, 1/4oz, 1/10oz) Three-coin set Year of the Snake

3,000

1,223

2002

$100, $25, $15

(1oz, 1/4oz, 1/10oz) Three-coin set Year of the Horse

3,000

1,471

2003

$100, $25, $15

(1oz, 1/4oz, 1/10oz) Three-coin set Year of the Goat

3,000

1,187

2004

$100, $25, $15

(1oz, 1/4oz, 1/10oz) Three-coin set Year of the Monkey

3,000

999

2005

$100, $25, $15

(1oz, 1/4oz, 1/10oz) Three-coin set Year of the Rooster

3,000

1,388

2006

$100, $25, $15

(1oz, 1/4oz, 1/10oz) Three-coin set Year of the Dog

3,000

1,274

2007

$100, $25, $15

(1oz, 1/4oz, 1/10oz) Three-coin set Year of the Pig

3,000

1,556

Still with mintages of 2,886 for the Proof Mouse, 3,146 for the Proof Ox and 1,223 (3rd lowest mintage of the sets) for the Proof Snake they wouldn't be easy to come by. However Series 2 is shaping up to have an even lower sales number even though the 1oz Gold Proof is now sold both individually and in the 3 coin set:

Year

Denomination

Description

Mintage

Sales

2008

$100

1oz Proof Lunar Mouse Coin 2008

3,000

141

2008

$100, $25, $15

(1oz, 1/4oz, 1/10oz) Three-coin set Year of the Mouse

3,000

1,036

2009

$100

1oz Proof Lunar Ox Coin 2009

3,000

131

2009

$100, $25, $15

(1oz, 1/4oz, 1/10oz) Three-coin set Year of the Ox

3,000

942

When added together there are 1177 1oz Proof Gold Mouse coins, under half of the 1996 release and 1073 1oz Proof Ox coins, almost a third of the 1997 release. So these are perhaps better coins to be on the look out for (although as I've already pointed out on the blog I think the cost of 1oz Gold coins will lower their ability to achieve large premiums like the Silver coins often manage).

While I don't think the Series 1 Proof Gold Mouse, Snake and Ox on eBay are expensive at the price point asked, I do think they would have limited appeal to the collector with the resources to collect coins this expensive as they would probably be looking to complete a set in their original form (in the 3 coin set).